18
Divisibility rule for 4
Textbook: Part 1, lesson 18, pp. 55–57
GoalKnow and use the divisibility rule for 4.
New words
last two digits · oxirgi ikki raqammultiple of 4 · 4 ga karralitwo-digit number · ikki xonali sonhundred · yuzlik
Explanation
Divisibility rule for 4: if the number formed by the last two digits is divisible by 4 (or the number ends in two zeros), the whole number is divisible by 4. The reason is that 100 is divisible by 4, so the hundreds do not matter. A number divisible by 4 is always even, but not every even number is divisible by 4 (for example 18).
Worked examples
5 316: the last two digits are 16 and 16 : 4 = 4, so the number is divisible by 4 (5 316 : 4 = 1 329).
7 342: the last two digits are 42, which is not divisible by 4, so 7 342 is not divisible by 4.
Class activity
“Two digits”: a child writes a number on a card and shows only its last two digits; classmates say whether the whole number is divisible by 4.
Practice
1
From 1 124, 3 058, 7 300, 5 614, 8 936 write those divisible by 4.
1 124, 7 300, 8 936
2
Which digits can replace the star so that 25* is divisible by 4?
2 or 6
3
Work out 1 000 : 4.
250
4
356 pictures were put into albums, 4 to an album. How many albums were needed?
89