có bao nhiêu hình vuông?

Nếu chữ số hàng trăm bớt đi (hay tăng thêm) 2 thì số đó giảm đi hay tăng thêm bao nhiêu đơn
vị?.......................................................................................
b) Số đó thay đổi thế nào nếu đổi chỗ chữ số 0 và chữ số 8 cho nhau?
Bài 16: a) Hai số có hai chữ số có cùng chữ số hàng chục mà chữ số hàng đơn vị hơn kém nhau
7 thì hai số đó hơn kém nhau bao nhiêu đơn vị?
b) Hai số có hai chữ số có cùng chữ số hàng đơn vị mà chữ số hàng chục hơn kém nhau 3 thì số đó
hơn kém nhau bao nhiêu đơn vị? bài giải nhé
 

đếm xem có bao nhiêu số 8 :

99999999999999999999999999999999999999999999999998999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999998999999999999999999999999999999999999999999998999999999999999999999999999999999999999999999999999999999999999999999989999999999999999999999999999999999989999999999999999999999999999999999999999899999999999999999999999999999999999899999999999999999999999999899999999999999999999999999899999999999999999999999899999999999999999999999999999999999999999998999999999999999999999999999989999999999999999999999999999999999999999999989999999999999999999999999999999999899999999999999999999999999999999999999999999999999999999999999999999989999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999899999999999999999999999999999999999999999999999999999999899999999999999999999999999999999999999999999999999999999899999999999999999999999999999999999999999999999999999999999999999999999999999989999999999999999999999999999999999999999999999999999998999999999999999999999999999999999999999999999999999999999999999999998999999999999999999999999999999999999999998999999999999999999999999999999999999999999999999899999999999999999999999999999999999999999999989999999999999999999999999999998999999999999999999999999999999999999999999