tim 1 số có 2 chữ số biết rằng khi viết thêm chữ số 4 vào bên trái chữ số đó ta được 1 số gấp 9 lần số phải tìm
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Những câu hỏi liên quan
NM
Nguyễn Minh Quang
Giáo viên
7 tháng 3 2021
1. khi thêm 4 vào bên trái số đó nghĩa là ta đã cộng thêm với 400
ta được số mới gấp 9 lần số ban đầu
nên 400 gấp 8 lần số ban đầu
hay số ban đầu là \(400:8=50\)
2. khi thêm 9 vào bên trái số đó nghĩa là ta đã cộng thêm với 900
ta được số mới gấp 13 lần số ban đầu
nên 900 gấp 12 lần số ban đầu
hay số ban đầu là \(900:12=75\)
HH
20 tháng 9 2014
Gọi số phải tìm là ab. Viết thêm chữ số 9 vào bên trái ta dược số 9ab. Theo bài ra ta có:
9ab = ab x 13
900 + ab = ab x 13
900 = ab x 13 – ab
900 = ab x (13 – 1)
900 = ab x 12
ab = 900: 12
ab = 75
20 tháng 7 2015
gọi số đó là abcd
abcd5=5x1abcd
abcdx10+5=50000+abcdx5
suy ra abcdx5=49995
nên abcd=49995:5
abcd=9999
vậy số đó là 9999
23 tháng 8 2015
Gọi số phải tìm là A. Nếu viết thêm chữ số 4 vào bên trái ta dược số 4A.Theo bài ra ta có:
94A = A x 9
400 + A = A x 9
400 = A x 9 – A
400 = A x (9 – 1)
400 = A x 8
A= 400: 8
A = 50
13 tháng 4 2016
Bai giai
goi so can tim la ab (a>0)
Khi viet them chu so 4 vao ben trai so can tim ta duoc mot so gap chin lan so phai tim( 9ab) va so do chia het cho 9. Neu a= 1;b= 4 -> 414 a= 2;b= 3 -> 423 a= 3;b= 2 -> 432 a= 4;b= 1 -> 441 a= 5;b= 0 -> 450 a= 6;b= 8 -> 468 a=7;b= 7 -> 477 a=8;b=6 -> 486 a=9;b=6 -> 496 Ta thay a=5;b=0 thi thoa man, vay so can tim la 50 bai nay dung day co giao minh giang bai nay ma
7 tháng 5 2018
Gọi x là số cần tìm Ta có
4000+x=9*x
4000=8*x
x=500
vậy số cần tìm là 500
2 tháng 5 2015
Gọi 3 số là abc
theo đb ta có
abc1=3 x 2abc
abc x 10 +1 =3x 2000+3abc
7 abc= 5999
abc=857
vậy số đó là 857
20 tháng 10 2018
857 dung 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Gọi số phải tìm là ab. Viết thêm chữ số 4 vào bên trái ta dược số 4ab. Theo bài ra ta có:
94ab = ab x 9
400 + ab = ab x 9
400 = ab x 9 – ab
400 = ab x (9 – 1)
400 = ab x 8
ab = 400: 8
ab = 50