54
Long division of two-digit numbers by two-digit numbers
Textbook: Part 2, lesson 54, pp. 48–50
GoalDividing a two-digit number by a two-digit number: choosing the quotient by trial.
New words
trial method · tanlash usuliquotient · bo‘linmaremainder · qoldiqdivisor · bo‘luvchi
Explanation
We choose the quotient: a number which, multiplied by the divisor, gives the dividend or a number just below it. The remainder must always be smaller than the divisor. 75 : 15: if we try 4, then 4 × 15 = 60 and the remainder is 75 − 60 = 15, which equals the divisor, so the guess was too small. Try 5: 5 × 15 = 75, remainder 0. The quotient is 5.
Worked examples
84 : 12: 7 × 12 = 84, so the quotient is 7 and there is no remainder.
93 : 21: 4 × 21 = 84, remainder 93 − 84 = 9 (and 9 < 21). 5 × 21 = 105 is bigger than 93. Answer: 4 (remainder 9).
Class activity
“Got it!”: the teacher says an example. Children write two guesses for the quotient (low and high), multiply to test and pick the right one.
Practice
1
96 : 16 = ?
6
2
91 : 13 = ?
7
3
90 : 22 = ? (with a remainder)
4 remainder 2
4
72 balls were shared equally among 24 pupils in the gym. How many balls does each pupil get?
3
5
A pump gives 12 l of water per minute. In how many minutes will it deliver 96 l?
8