31
Multiplying a multi-digit number by a two-digit number
Textbook: Part 1, lesson 31, pp. 96–98
GoalMultiply a multi-digit number by a two-digit number in a column.
New words
multi-digit number · ko‘p xonali sonmultiplying place by place · xonama-xona ko‘paytirishwriting shifted left · chapga surib yozishfare · yo‘lkira
Explanation
The two-digit number is written under the multi-digit number (ones under ones). Multiply the first number by the ones of the second, then by its tens; the second product starts one place further left. Then add the two products.
Worked examples
4 718 × 36: 4 718 × 6 = 28 308; 4 718 × 30 = 141 540; the sum is 169 848.
3 125 × 48 = 3 125 × 8 + 3 125 × 40 = 25 000 + 125 000 = 150 000.
Class activity
“Multiplication race”: two teams solve the same problem (for example 6 205 × 24) in a column at the board. The first correct team wins; a mistake costs a point.
Practice
1
6 205 × 24 = ?
148920
2
12 318 × 52 = ?
640536
3
600 735 × 46 = ?
27633810
4
A trip costs 1 600 so‘m. Sardor goes to school and back 26 days a month (2 trips a day). How many so‘m does he spend on fares per month?
83200
5
One person needs about 41 000 so‘m per day for food. How many so‘m does one person need in autumn (91 days)?
3731000