1)viet day tu nhien tu 1-101 tao thanh so A 

a) A co phai hop so khong

b)A co phai so chinh phuong khong

c)A co the co 35 uoc khong

2)tim so chinh phuong co 4 chu so chu so hang nghin bang chu so hang don vi va so do co the viet duoi dang (5n+4)²

tim so chinh phuong co 4 chu so sao cho 2 chu so dau tao thanh so chinh phuong va 2 chu so cuoi cung tao thanh so chinh phuong 

tim a, b de A= aabb la so chinh phuong . Trong do aabb la 1 STN co 4 cs

tim mot so chinh phuong co 4 chu so vua la so chinh vua la so lap phuong

Tim so chinh phuong co 4 chu so sao cho khi bot moi chu so di 1 don vi ta cung duoc so chinh phuong

tim so chinh phuong co 4 chu so ,biet rang neu lay chu so hang nghin tru di 3, chu so hang don vi cong them 3 thi duoc so moi cung la so chinh phuong

tim so co 4 chu so abcd, biet rang abd la so chinh phuong, neu cong them 72 don vi thi duoc mot so chinh phuong

tim so chinh phuong co 4 chu so gom ca bon chu so 7,4,2,0