Addition and Subtraction Up to 99 Class 1 Notes Maths

Addition

Adding 1-Digit and 2-Digit Numbers up to 99

Shelly has 15 hair clips. She got 4 more. How many hair clips does Shelly have now? To know the total number of hair clips with Shelly, we add 15 and 4 using the following steps.

Step 1: Add the ones.

Step 2: Add the tens.

Shelly has 19 hair clips now.

Adding 2-Digit Numbers

A florist has 32 red roses and 24 orange roses.
How many roses does he have altogether?
To know how many roses does the florist have in all, we add 32 and 24 as follows in two steps.

Step 1: Add the ones.

Step 2: Add the tens.

Thus, the florist has 56 roses altogether.

Subtraction

Subtracting a 1-Digit Number from a 2-Digit Number

Somya had a collection of 19 hair bands. She lost 5. How many hair bands are left with her?
To find the number of hair bands left with Somya, we subtract 5 from 19 in two steps as follows.

Step 1: Subtract the ones.

Step 2: Subtract the tens.

Thus, Somya is left with 14 hair bands.

Subtracting 2-Digit Numbers

Ravi had 36 marbles. He gave 22 to his friend Anil. How many marbles are left with him?
To find how many marbles are left with Ravi, we subtract 22 from 36 in two steps as follows.

Step 1: Subtract the ones.

Step 2: Subtract the tens.

Thus, 14 marbles are left with Ravi.

More Ways of Addition and Subtraction

1. Addition by splitting the numbers pictorially

Add 42 and 33.

Step 1: Split the numbers into tens and ones.

Step 2: First add the ones together then add the tens together.

Step 3: Now, combine the tens and ones to get the sum.

= 7 tens + 5 ones
= 70 + 5
= 75
Thus, 42 + 33 = 75.

2. Subtraction by splitting the numbers pictorially
Subtract 32 from 43.

Step 1: Split the greater number 43 into tens and ones.

Step 2: Subtract the ones.

3 - 2 = 1

Step 3: Subtract the tens.

40 - 30 = 10

We are left with

= 1 ten + 1 one
= 10 + 1 = 11
So, 43 - 32 = 11.

3. Addition and subtraction using expanded form
Add: 23 + 46

Subtract: 69 – 23