Rapid Mental Calculation Tips - Addition

Calculate from Left to Right

The key to do rapid mental math addition is to calculate from left to right, rather than right to left. In a traditional way, your may add up two numbers from right to left. For example, 234 + 345, you may add the ones digit first (234 + 5 = 239), then follow by the tens digit (239 + 40 = 279) and lastly the hundreds digit (279 + 300 = 579).

However, if you wish to calculate faster just in your mind, with no pencil and paper, it’s more natural and faster to add from left to right. For example, to calculate 567 + 432, we add the hundreds digit first (567 + 400 = 967), then the tens digit (967 + 30 = 997) and lastly the ones digit (997 + 2 = 999).

Let's have a few practices.

Question 1
7,415 + 2,363 =

Steps:
7,415 + 2,000 = 9,415
9,415 + 300 = 9,715
9,715 + 60 = 9,775
9,775 + 3 = 9,778

or in our mind,

7,415 → 9,415 → 9,715 → 9,775 → 9,778

Question 2
25,613 + 63,345 =

Solution

25,613 → 85,613 → 88,613→ 88,913 → 88,953 → 88,958

Question 3
571 + 376 =

Solution

571 → 871 → 941→ 957

Question 4
7,153 + 3,483 =

Solution

7,153 → 10,153 → 10,553→ 10,633 → 10,636


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