Q.) The last two-digits in the multiplication

122 X 123 X 125 X 127 X 129 will be

(a) 20

(b) 50

(c) 30

(d) 40

Solution :

One way is to multiply all the given number (Brute force method) and this would give you the last two digits.

Other way:

Here , one of the number is a multiple of 5 and the other is a multiple of 2.

122 X 125 = 15250 lasts with 50 as last two digits.

This multiplied by odd numbers will always give 50 as the last two digits.

Hence , Option(b)