56
Long division by a three-digit number
Textbook: Part 2, lesson 56, pp. 54–56
GoalLong division by a three-digit number works just like division by a two-digit number.
New words
three-digit number · uch xonali sonestimate · taxminproduct · ko‘paytmadifference · ayirma
Explanation
When the divisor has three digits we repeat the same steps as for a two-digit divisor; only the incomplete dividend is larger. Round the divisor to hundreds to estimate the quotient. 3 354 : 258: 335 : 258 = 1 (remainder 77), then 774 : 258 = 3. The quotient is 13. Check: 258 × 13 = 3 354.
Worked examples
1 872 : 234: 187 < 234, so we take all 4 digits: 1 872 : 234 = 8, because 234 × 8 = 1 872.
2 142 : 306 = 7, because 306 × 7 = 2 142.
Class activity
“Big divisor”: in pairs, one child picks a three-digit divisor and a quotient, the other multiplies to get the dividend and then divides it by the three-digit number.
Practice
1
5 082 : 154 = ?
33
2
9 936 : 276 = ?
36
3
7 280 : 364 = ?
20
4
One wagon holds 105 t of coal. How many wagons are needed to carry 1 785 t of coal?
17