GMAT tests your logical skills as well as your knowledge of math concepts. To score high, you need to remember various formulas, theorems. Also you need to master critical problem-solving skills.
Today I am going to take you through one problem -solving skill –
Attention to detail
Take this problem .
I am going to show you, two ways to solve this sum
Method 1 : The traditional approach
You need to choose the numbers which negate each other
For example Row 6 column 6 = 36.
Row 5 column 6 = -30 and Row 1 column 6 is -6
So 36+ (-30-6) =0.
You need to choose the right numbers
Add the remaining numbers you will get the answer
I have highlighted the different combinations with letters
I have highlighted the different combinations with letters
| 1J | -2I | 3H | -4J | 5D | -6A |
| -2 | 4G | -6C | 8G | -10I | 12I |
| 3J | -6B | 9H | -12H | 15E | -18B |
| -4F | 8G | -12F | 16F | -20E | 24B |
| 5E | -10 | 15 | -20G | 25D | -30D |
| -6 | 12 | -18C | 24C | -30A | 36A |
Numbers left = 12 15 -6 -10 -2
Sum = 9
This method takes a long time
Method 2: Pattern recognition
This approach is a lot faster.
If you look at the numbers column-wise can you see a pattern(ignore signs)
column 1: 1 2,3,4,5,6
column 2: 2×1,2×2,2×3,2×4,2×5,2×6
.
.
column 6: 6×1,6×2,6×3………..6×6
When the signs are inserted, then a pattern emerges i.e. = 1-2+3-4+5-6
lets calculate the sum of the repeating pattern 1-2+3-4+5-6 = -3
Hence column 1 adds upto -3
Next column will be -2+4-6+8-10+12 = -2 x(1-2+3-4+5-6)= -2x-3 = 6
Next column will be 3 x(1-2+3-4+5-6)= 3 x-3 = -9
Next column will be -4 x(1-2+3-4+5-6)= -4 x-3 = 12
Next column will be 5 x(1-2+3-4+5-6)= 5 x-3 = -15
Next column will be -6 x(1-2+3-4+5-6)= -6 x-3 = +18
Answer = -3+6-9 +12-15+18 = 9
If you want to maximize your math scores in the GMAT.. Lets have a chat…
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Lets try another sum
