Ex 1.2, 8 (Method 1) A student multiplied 7236 by 65 instead of multiplying by 56. By how much was his answer greater than the correct answer? (Hint: Do you need to do both the multiplications?)
Wrong multiplication = 7236 × 65
Right multiplication = 7236 × 56
Difference between both answers
= 7236 × 65 − 7236 × 56
Taking 7236 common
= 7236 × (65 − 56)
= 7236 × 9
So, wrong answer was greater than right answer by 65,124.
Ex 1.2, 8 (Method 2) A student multiplied 7236 by 65 instead of multiplying by 56. By how much was his answer greater than the correct answer? (Hint: Do you need to do both the multiplications?)Wrong multiplication
= 7236 × 65
Difference between wrong answer and right answer
= 4,70,340 − 4,05,216
So, wrong answer was greater than right answer by 65,124.

Article by

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.