Question

estimate the product and verify by calculation 715×395​

Answer 1

The product can be estimated to be 715x395 = close to 710x400 = 284000

Verifying by calculation,

• 715 x 395 = (700 +15)  x ( 400 - 5 )  =

• product  = 700x400 + 15 x 400 - 5x 700 - 5x15 =

• product = 280000 + 6000 -3500 - 75 = 280000 + 2425 = 282425

• We can see that by estimating we got a very close value compared to the size of the number.
• SInce its in the order of 2.84 x 10^5, error of 0.01575 is acceptable only based on the context.

• If its mandatory to have an accurate value, we should calculate it . Else we can estimate as above.