5
Review: properties of 0 and 1
Textbook: Part 1, lesson 5, pp. 16–18
GoalKnow and use the properties of the numbers 0 and 1.
New words
zero · nolone · birproperty · xossadivision is impossible · bo‘lish mumkin emas
Explanation
Multiplying or dividing any number by 1 leaves it unchanged: a × 1 = a, a : 1 = a. Any number times 0 is 0: a × 0 = 0. Zero divided by a non-zero number is 0. A number divided by itself is 1. Division by 0 is impossible.
Worked examples
358 × 1 = 358; 0 × 947 = 0; 625 : 625 = 1; 0 : 83 = 0.
(15 − 15) × 48 = 0 × 48 = 0, because the brackets give 0.
Class activity
“Magician of zero and one”: children hold cards “× 1”, “× 0” and “: 1”. The teacher names a number and an operation and children write the correct result on the board.
Practice
1
(15 − 15) × 48 = ?
0
2
712 : 1 = ?
712
3
29 × 1 + 0 × 29 = ?
29
4
x : 1 = 67. Find x.
67
5
Is division by zero possible? (Answer “Yes” or “No”.)
No, division by zero is impossible.