Question

[Nguyễn Ngọc Anh]

Mỗi số sau có bao nhiêu ước?

60; 72; 25; 102; 123.

Answer 1

[Nguyễn Hoàng Minh]

\(60=2^2\cdot3\cdot5\) có \(\left(2+1\right)\left(1+1\right)\left(1+1\right)=12\left(ước\right)\)

\(72=2^3\cdot3^2\) có \(\left(3+1\right)\left(2+1\right)=12\left(ước\right)\)

\(25=5^2\) có \(5+1=3\left(ước\right)\)

\(102=2\cdot3\cdot17\) có \(\left(1+1\right)\left(1+1\right)\left(1+1\right)=8\left(ước\right)\)

\(123=3\cdot41\) có \(\left(1+1\right)\left(1+1\right)=4\left(ước\right)\)