89
More/fewer with diagrams
Textbook Part 3, pp. 32–33
GoalShow more/fewer problems with diagrams; increase a digit in one place.
New words
larger number · katta sonsmaller number · kichik songuide · gid
Explanation
In a diagram we draw two bars, one longer than the other. The extra piece shows “... more”. Larger number = smaller number + difference; smaller number = larger number − difference.
Worked examples
A live guide talks for 12 minutes and a virtual guide 5 minutes less: 12 − 5 = 7 minutes.
Increase the tens digit of 34 by 5: 84 (34 + 50).
Class activity
Paper strips: children cut two strips (one 3 squares longer) and make up a problem about them.
Practice
1
Increase the ones digit of 72 by 2.
74
2
Increase the tens digit of 28 by 7.
98
3
Larger number 45, difference 12. Smaller number?
33
4
Smaller number 23, difference 14. Larger number?
37