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Hi Abhishek,
I am having difficulties after rounding up and subtracting the amount.
For Example: For 67×8, i would round up the first number by 3 to 70 and multiply it by 8 and it will get 560 and similarly for the rounded up value 3×8=24. So, how do i apply the round up technique here while subtracting 84 from 560? I am getting 516 as the answer as the last digit adds up to 10 and other adds upto 9..
I know its silly but i think am getting frequently stuck and confused.
Here are the steps:
We are trying to multiply
= 67 x 8.
We break down 67 into (70 – 3). So we get:
= (70 – 3) x 8
Multiplying the individual numbers we have.
= 560 – 24
LR Subtraction without Round Up.
Here we subtract left to right.
560 – 24 = _ _ _
First number is 5 so it becomes the first digit of the answer.
560 – 24 = 5 _ _
Second digits is 6 – 2 = 4 it becomes the second digit of the answer.
560 – 24 = 5 4 _
We cannot subtract 0 – 4 so we must borrow 1 from the existing answer 54 so it becomes 53.
560 – 24 = 53 _
Now we subtract 10 – 4 to get 6 which is the last digit of the answer.
560 – 24 = 536.
Alternative LR Subtraction with Round Up.
If you want to do the LR Subtraction with round up, then here are the steps. To recap we are trying to subtract
560 – 24 = _ _ _
We can round up 24 to 30 so the equation becomes:
560 – (30 – 6) = _ _ _
530 – 30 + 6 = _ _ _
We subtract 560 – 30 to get 530
560 – 30 = 530.
We add the amount we rounded up which is 6 to get 536.
530 + 6 = 536.
536 is the final answer for 67 x 8.
Hope this clarifies.
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