Square of a number having 5 at its one’s place and 2 or more digits at its ten's, hundred's,......etc. place is equal to 25 followed by the product of the number of the remaining digits and the number exceeded by 1.
You may write the products in one line.
a) 5 5 (b) 6 5 (c) 7 5 (d) 1 0 5
x 5 5 x 6 5 x 7 5 x 1 0 5
______ ______ ______ _______
(e) 2 0 5 (f) 3 4 5 (g) 9 9 5
x 2 0 5 x 3 4 5 x 9 9 5
________ ________ ________
Check answers:
(a) 3025
5 x 6 = 30
(b) 4225
6 x 7 = 42
(c) 5625
7 x 8 = 56
(d) 11025
10 x 11 = 110
(e) 42025
20 x 21 = 420
(f) 119025
34 x 35 = 1190
(g) 990025
99 x 100 = 9900
Related Concept
● Patterns and Mental Mathematics
● Counting Numbers in Proper Pattern
● Puzzle
● Patterns
4th Grade Math Activities
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