Question paper, Set 3

(i) Start at $5$ and count on $1$: $1 + 5 = 6$

(ii) Count back $1$ from $3$: $3 - 1 = 2$

Answer: (i) $6$ (ii) $2$

$6$ needs $4$ to make $10$; take $4$ from $6$, which leaves $2$.

$6 + 6 = 10 + 2 = 12$

Answer: $\square = 2$; $6 + 6 = 12$

$\square = 6 - 3 = 3$

Check: $3 + 3 = 6$

Answer: $3$

(i) $50 = 40 + 10$ and $10 - 2 = 8$, so $50 - 2 = 40 + 8 = 48$

(ii) $90 = 80 + 10$ and $10 - 5 = 5$, so $90 - 5 = 80 + 5 = 85$

Answer: (i) $48$ (ii) $85$

Take $3$ from the units digit: $6 - 3 = 3$; the tens digit $5$ stays.

$56 - 3 = 53$

Answer: $53$

1st method: take $1$ out of $5$ first ($5 - 1 = 4$): $11 - 5 = 10 - 4 = 6$

2nd method: add $5$ to both: $11 - 5 = 16 - 10 = 6$

Both methods give $11 - 5 = 6$

Answer: $6$

1st method: take $6$ out of $8$ first ($8 - 6 = 2$): $36 - 8 = 30 - 2 = 28$

2nd method: add $2$ to both: $36 - 8 = 38 - 10 = 28$

3rd method: $36 - 10 = 26$ and $10 - 8 = 2$, so $36 - 8 = 26 + 2 = 28$

All three methods give $36 - 8 = 28$

Answer: $28$

$9$ tens $-$ $8$ tens $=$ $1$ ten

$90 - 80 = 10$

Answer: $10$

1st method (take the tens first): $97 - 78 = 27 - 8 = 20 - 1 = 19$

2nd method: add $2$ to both: $97 - 78 = 99 - 80 = 19$

3rd method: $97 - 80 = 17$ and $80 - 78 = 2$, so $97 - 78 = 17 + 2 = 19$

4th method (column): $7 < 8$, so borrow $1$ ten: units $17 - 8 = 9$, tens $8 - 7 = 1$

All four methods give $97 - 78 = 19$

Answer: $19$

(i) $490 = 480 + 10$ and $10 - 8 = 2$, so $490 - 8 = 480 + 2 = 482$

(ii) units $7 - 1 = 6$, tens $6 - 2 = 4$, hundreds $4$ stays: $467 - 21 = 446$

Answer: (i) $482$ (ii) $446$

1st method (take the tens first): $271 - 58 = 221 - 8 = 220 - 7 = 213$

2nd method: add $2$ to both: $271 - 58 = 273 - 60 = 213$

3rd method: $271 - 60 = 211$ and $60 - 58 = 2$, so $271 - 58 = 211 + 2 = 213$

4th method (column): $1 < 8$, so borrow $1$ ten: units $11 - 8 = 3$, tens $6 - 5 = 1$, hundreds $2$

All four methods give $271 - 58 = 213$

Answer: $213$

Take away the tens first: $100 - 60 = 40$

$100 - 65 = 40 - 5 = 35$

Answer: $35$

1st method (column): units $3 < 7$, borrow $1$ ten: $13 - 7 = 6$

tens: $3 < 5$, borrow from the hundred: $13 - 5 = 8$, hundreds $0$

2nd method: take $3$ from both: $143 - 57 = 140 - 54$

take $40$ from both: $= 100 - 14 = 86$

3rd method: $143 - 100 = 43$ and $100 - 57 = 43$, so $143 - 57 = 43 + 43 = 86$

All three methods give $143 - 57 = 86$

Answer: $86$

$1$ ten $+$ $5$ tens $=$ $6$ tens

$10 + 50 = 60$

Answer: $60$

Tens: $40 + 30 = 70$

Units: $5 + 1 = 6$

$45 + 31 = 70 + 6 = 76$

Answer: $76$

$70 \div 8$: $8 \times 8 = 64$, $70 - 64 = 6$

Bring down $1$, we have $61$: $8 \times 7 = 56$, $61 - 56 = 5$

Bring down $6$, we have $56$: $8 \times 7 = 56$, $56 - 56 = 0$

Remainder $0$, so $7016 \div 8 = 877$

Answer: $877$

$6 \div 2$: $2 \times 3 = 6$, $6 - 6 = 0$

Bring down $8$, we have $8$: $2 \times 4 = 8$, $8 - 8 = 0$

Bring down $3$, we have $3$: $2 \times 1 = 2$, $3 - 2 = 1$

Bring down $9$, we have $19$: $2 \times 9 = 18$, $19 - 18 = 1$

Bring down $9$, we have $19$: $2 \times 9 = 18$, $19 - 18 = 1$

Bring down $0$, we have $10$: $2 \times 5 = 10$, $10 - 10 = 0$

Bring down $4$, we have $4$: $2 \times 2 = 4$, $4 - 4 = 0$

Remainder $0$, so $6839904 \div 2 = 3419952$

Answer: $3419952$

$72 \div 8$: $8 \times 9 = 72$, $72 - 72 = 0$

Bring down $6$, we have $6$: $6 < 8$, so write $0$ in the quotient

Bring down $5$, we have $65$: $8 \times 8 = 64$, $65 - 64 = 1$

Bring down $6$, we have $16$: $8 \times 2 = 16$, $16 - 16 = 0$

Remainder $0$, so $72656 \div 8 = 9082$

Do not miss the $0$ in the quotient.

Answer: $9082$

$48 \div 11$: $11 \times 4 = 44$, $48 - 44 = 4$

Bring down $1$, we have $41$: $11 \times 3 = 33$, $41 - 33 = 8$

Bring down $8$, we have $88$: $11 \times 8 = 88$, $88 - 88 = 0$

Remainder $0$, so $4818 \div 11 = 438$

Answer: $438$

$\displaystyle \frac{24}{4}$ means $24 \div 4$.

$4 \times 6 = 24$, so $\displaystyle \frac{24}{4} = 6$

Answer: $6$