- Mental math is a skill that helps students to do math in their heads without using paper and pencil.
- Mental Math is useful in school and everyday life.
- It also helps to do calculations faster.

In subtraction,

- The larger number is called the minuend.
- The smaller number is called the subtrahend.
- The resultant number is called the difference.

**Method 1:**(Add, and subtract)

- Express the subtrahend as the difference of the nearest hundred in a one/two-digit number.
- Then do the subtraction while adding the one/two-digit number with the minuend

**Example:**

**Answer:**

Now, 189 = 200 – 11

So, 278 – 200 + 11 = 78 + 11 = 89

**Method 2:**(Split the Problems)

- The basic idea is to split the minuend and subtrahend into two or more numbers which are easier to work with.
- While splitting we will obviously take one number which is nearest to the hundred.

**Example:**

**Answer:**

- 568 = (500 + 68)

329 = (300 + 29)

Now, 500 – 300 = 200

68 – 29 = 39

So, 200 + 39 = 239

Hence, 568 – 329 = 239

b.

**Method 3:**(Nikhilam rule)

- Nikhilam rule says that “All from 9 and the last from 10.”
- That means all digits should be subtracted from 9 and the last digit should be subtracted from 10.
- After the subtraction, the difference should be added to the minuend.
- Deleting the left first digit of the sum of the minuend and the result, we get the final result of the subtraction.

**Example:**

**Answer:**

- We need to subtract 123 from 9910 like the following way

b. 897 – 250 =

We need to subtract 250 from 9100 like the below way

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