IMPORTANT TIP: ADDITION using "Rainbow Method"


Today's math tip is applicable across all levels as this kind of question have been getting more and more popular over the years!

Using "Rainbow method" known as Gauss Method by a famous Mathematician (Carl Friedrich Gauss), pair the numbers in sequence.

Basic: What is the sum of 1 to 10?

1+2+3+4+5+6+7+8+9+10 = ?

Pair the following numbers eg:

1 + 10 = 11

2 + 9 = 11

3 + 8 = 11

4 + 7 = 11

5 + 6 = 11

There, you have 5 pairs of (11) = 5 x 11 = 55

Therefore,

1 + 10 = 11 (Sum of a pair)

10 ÷ 2 = 5 (divided by 2 as each set consist of 2 numbers)

5 x 11 = 55

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Advanced Question: What is the sum of 1 to 100?

1 + 2 + 3 + 4 + … + 98 + 99 + 100 = ?

1 + 100 = 101 2 + 99 = 101 3 + 98 = 101 . . . 48 + 53 = 101 49 + 52 = 101 50 + 51 = 101

Solution:

1 + 100 = 101

100 ÷ 2 = 50 (there are 50 sets of 101)

50 x 101 = 5050

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Advanced Question: What is the sum of 1 to 59?

1 + 2 + 3 + 4 + … + 98 + 99 = ?

Solution:

1 + 59 = 60

59 ÷ 2 = 29.5

29.5 x 60 = 1770

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