Gọi số cần tìm là ab
Ta có: abx9=a1b
=> (ax10+b)x9=ax100+10+b
=> ax90+bx9=ax100+10+b
=> bx9-b=ax100-ax90+10
=> bx8=ax10+10
=> bx8= 10x(a+1)
=> b=5;a+1=4
=> b=5;a=3
Vậy số cần tìm bằng 35
tim so co hai chu so biet rang neu ta viet them chu so 1 vao giua 2 chu so cua so do ta duoc so moi gap 9 lan so phai tim
tim so co 2 chu so biet rang neu ta viet them chu so 1 vao giua 2 chu so cua so do ta duoc so moi gap 9 lan so phai tim
tim so co hai chu so biet rang neu viet them chu so 1 vao giua 2 chu so thi ta duoc so moi gap 9 lan so phai tim
tim mot so co hai chu so biet rang neu viet them chu so 0 xen vao giua chu so hang chuc va hang don vi cua so do ta duoc so moi va neu viet them chu so hai vao ben trai so moi thi ta duoc mot so gap 6 lan so moi do
tim mot so co hai chu so biet rang ta viet them chu so 1 va giua hai chu so cua so do ta duoc so moi gap 9 lan so phai tim. trai loi: so phai tim la ... cac giai luon nhe!
tim so co 2 chu so, biet rang neu ta viet them chu so 1 vao giua 2 so cua so do ta duoc so moi gap so can tim 9 lan. tinh so ban dau
tim 1 so tu nhien co 2 chu so biet neu viet them chu so 0 vao giua hai chu so cua so do ta duoc so moi bang 7 lan so phai tim
tim mot so co hai chu so biet rang neu viet them vao giua so do mot so co hai chu so kem so phai tim 1 don vi thi duoc mot so moi gap 91 laan so phai tim tim hai so
tim so tu nhien co 2 chu so biet rang neu viet chu so 0 xen giua chu so hang chuc va hang don vi cua so do ta duoc so moi gap 10 lan so can tim . Neu viet them chu so 1 vao ben trai so vua nhan duoc thi so do gap len 3 lan . So can tim la
