Addition Tricks (2)
Algebra
Level
1
Given the number 100, you are tasked to do the following:
- First, add 7 to the number
- Second, add 10 to the number
- Third, add 6 to the number
- Fourth, add 10 to the number
- Fifth, add 14 to the number
- Sixth, add 10 to the number
- Lastly, add 13 to the number
What is the result?
- Mental Math Tricks wiki
- Check out the set .
The answer is 170.
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1 solution
We intend to attack those numbers whose unit digits sum up to 10.
The answer is of the form 1 0 0 + [ 7 + 1 0 + 6 + 1 0 + 1 0 + 1 4 + 1 0 + 1 3 ]
= 1 0 0 + [ ( 7 + 1 3 ) + ( 1 4 + 6 ) + ( 1 0 + 1 0 + 1 0 ) ]
= 1 0 0 + ( 2 0 + 2 0 + 3 0 )
= 1 0 0 + 7 0
= 1 7 0