Question

use divison algorithm to show that the square of any positive integer is of the form 5n+0, 5n+1, 5n+4

Answer 1

now we can find

1. 1=5(0)+1=1 (5n+1)
2. 4=5(0)+4=4 (5n+4)
3. 9=5(1)+4=9 (5n+4)
4. 16=5(3)+1=16 (5n+1)

like this we can prove this