27
Multiplying a three-digit number by a one-digit number
Textbook: Part 1, lesson 27, pp. 84–86
GoalMultiply a three-digit number by a one-digit number in a column.
New words
three-digit number · uch xonali sonone-digit number · bir xonali sonhundreds · yuzliklarmultiplication · ko‘paytirish
Explanation
Write the one-digit number under the three-digit number and multiply it by the ones, tens and hundreds in turn. In each place write the ones of the product and carry the tens to the next place. We can also use place-value addends: 354 × 7 = 300 × 7 + 50 × 7 + 4 × 7. The larger number goes on top.
Worked examples
354 × 7 = 300 × 7 + 50 × 7 + 4 × 7 = 2100 + 350 + 28 = 2478.
471 × 5: 1 × 5 = 5; 7 × 5 = 35 (write 5, carry 3); 4 × 5 = 20, 20 + 3 = 23. Answer: 2 355.
Class activity
“Big on top”: children pair five three-digit cards with five one-digit cards and write each pair in a column the right way round to multiply.
Practice
1
243 × 9 = ?
2187
2
716 × 4 = ?
2864
3
5 × 387 = ?
1935
4
A bag costs 285 thousand so‘m, with a discount 199 thousand. How many thousand so‘m are saved on 4 bags bought at the discount?
344
5
A shirt costs 135 thousand so‘m and trousers 64 thousand. How many thousand so‘m do 4 sets, each with a shirt and trousers, cost?
796