1
Tens and ones to 30
Joyful Mathematics: Chapter 8
GoalShow the numbers 21 to 30 as tens and ones.
New words
ten · a group of 10 thingsones · single things left overtwenty-three · how we say 23
Explanation
Count in groups of ten. Two tens make 20. Add some single ones. 2 tens and 3 ones make 23. In 23, the 2 tells the tens and the 3 tells the ones. Three tens make 30.
Worked examples
On Diwali night Kabir set out 2 rows of 10 oil lamps and 4 more lamps. That is 2 tens and 4 ones, so 24 lamps.
For Makar Sankranti, Meera has 2 bundles of 10 kites and 7 kites more. That is 2 tens and 7 ones, so 27 kites.
3 groups of 10 stars make 30 stars. There are no ones left over.
Class activity
Pebble piles. Count out exactly 26 pebbles, one by one. Make piles of 10. How many full piles do you have? How many pebbles are left over? Say: two tens and six ones, twenty-six.
Practice
1
Count the tens and the ones. Which number is this?
22
2
Write the number for 2 tens and 9 ones.
29
3
How many flowers are there? Write the number.
26
4
What number is 3 tens and 0 ones?
30
5
In 28, how many tens and how many ones?
2 tens and 8 ones.