Tìm x: (bài này trong đề thi của mikđo giải giùm nhe mà phải đúng nữa . Thanks ) 2x+4 + 2x = 34
Bạn Trâm đánh dấu các số trang từ 1 -> 100. Hỏi cần bao nhiêu chữ số để đánh hết số trang ?
K
Khách
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Những câu hỏi liên quan
28 tháng 7 2020
A)
- Từ 1 đến 9 có 9 số,gồm 9 chữ số.
- Từ 10 đến 99 có 90 số,gồm 180 chữ số.
- Từ 100 đến 200 có 101 số,gồm 202 chữ số.
Số chữ số cần dùng để đánh số trang của 1 quyển sách dày 200 trang là:
9 + 180 + 202 = 391 ( chữ số )
( mik cx ko biết có đúng ko nx,nhưng theo mik là zậy )
Chúc học tốt nha !!!
MA
28 tháng 7 2020
a/ Đánh số trang từ 1 đến 9 cần số chữ số là :[ (9 - 10 ) : 1 +1 ] x 1 =9 ( chữ số )
Đánh dấu trang từ 10 đến 99 cần số chữ số là : [(99 - 10) : 1 +1 ] x 2 =180 ( chữ số )
Đánh dấu trang từ 100 đến 200 cần số chữ số là : [ ( 200 -100 ) : 1 + 1 ] x3 = 303 ( chữ số )
Đánh dấu trang một quyển sách gồm 200 trang cần số chữ số là :9+180+303= 492 ( chữ số )
Đáp số : 492 chữ số.
15 tháng 6 2021
1/Để đánh số trang của quyển sách đó cần:
\([\left(9-1\right):1+1]+[\left(99-10\right):1+1]\times2+[\left(248-100\right):1+1]\times3=636\)(chữ số)
16 tháng 8 2017
bn ơi !!
bt1 là 5050 công thức : số đầu cộng số cuối nhân sổ số hạng chia 2 ok
k mik nha
18 tháng 7 2018
Từ trang 3 đến trang 9 có:
( 9 - 3) : 1 + 1 = 7 ( số có một chữ số )
Từ trang 10 đến trang 99 có:
( 99 - 10 ) : 1 + 1 = 90 ( số có hai chữ số )
Từ trang 100 đến trang 132 có:
( 132 - 100 ) : 1 + 1 = 33 ( số có ba chữ số )
Vậy số chữ số phải dùng là:
1 x 7 + 90 x 2 + 33 x 3 = 286 ( chữ số )
Đáp số: 286 chữ số
Hộc tốt nhé!
20 tháng 9 2016
1. 31/23 - (7/32 + 8/23)
= 31/23 - 7/32 - 8/23
= 31/23 - 8/23 - 7/32
= 32/32 - 7/32 (1=32/32)
= 25/32
BD
20 tháng 9 2016
câu 1 : dùng máy tính để tính cho nhanh , mỗi phân số lấy tử chia mẫu nha
câu 2 : ta có
2015 trang mà
1 đến 9 có : 9 chữ số
10 đến 99 có : 180 chữ số
100 đến 999 có : 2700 chữ số
1000 đến 1999 có : 4000 chữ số
2000 đến 2015 có : 64 chữ số
vậy có tất cả : 9 + 180 + 2700 + 4000 + 64 = 6953 ( chữ số )
câu 3 : ta có
1 đến 9 có : 9 chữ số
10 đến 99 có : 180 chữ số
100 đến 999 có : 2700 chữ số
1000 đến 1975 có : 3904 chữ số
tổng : 9 + 180 + 2700 + 3904 = 6793
Vậy trang cuối là trang 6793
mong các bạn ủng hộ !
DD
Đoàn Đức Hà
Giáo viên
24 tháng 1 2021
a) Số trang có một chữ số là: \(9\).
Số trang có hai chữ số là: \(90\).
Số trang có ba chữ số là: \(\left(172-100\right)+1=73\).
Số chữ số cần dùng là: \(1.9+2.90+3.73=408\).
b), c) bạn làm tương tự.
28 tháng 5 2019
3,Chữ số hàng nghìn là :
153 : 5 dư 3
=> cs hàng nghìn là : 5
28 tháng 5 2019
3,Chữ số hàng nghìn là :
153 : 5 dư 3
=> cs hàng nghìn là : 5
LA
13 tháng 11 2015
sồ trang từ 1->9 có tổng cộng 9 chữ số
số các số từ 10->99 là (99-10):1+1=90 (số)
số trang từ 10->99 có tổng cộng 90 nhân 2 = 180 chữ số
số các số từ 100 ->265 là (265-100):1+1=166 (số)
số trang từ 100->265 có tổng cộng 166 nhân 3 = 498 chữ số
em phải đánh số chữ số là : 9+180+498=587 chữ số
(=) 2x.24+2x=34
(=) 2x.(16+1)=34
(=) 2x.17 =34
(=) 2x =2
=) x = 1
vậy.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................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Các số từ 1 đến 9 có 9 chữ số.
Các số từ 10 đến 99 có 90 số và có số chữ số là: 90 x 2 = 180 chữ số
Số 100 có 3 chữ số nên sẽ cần số chữ số là: 9 + 180 + 3 = 192 chữ số
Đáp số: 192 chữ số
Chúc bạn học tốt!