Question paper, Set 1

(i) Start at $9$ and count on $1$: $1 + 9 = 10$

(ii) Count back $1$ from $4$: $4 - 1 = 3$

Answer: (i) $10$ (ii) $3$

$8$ needs $2$ to make $10$; take $2$ from $5$, which leaves $3$.

$5 + 8 = 10 + 3 = 13$

Answer: $\square = 3$; $5 + 8 = 13$

$\square = 6 - 4 = 2$

Check: $4 + 2 = 6$

Answer: $2$

(i) $90 = 80 + 10$ and $10 - 2 = 8$, so $90 - 2 = 80 + 8 = 88$

(ii) $60 = 50 + 10$ and $10 - 7 = 3$, so $60 - 7 = 50 + 3 = 53$

Answer: (i) $88$ (ii) $53$

Take $6$ from the units digit: $6 - 6 = 0$; the tens digit $2$ stays.

$26 - 6 = 20$

Answer: $20$

1st method: take $2$ out of $6$ first ($6 - 2 = 4$): $12 - 6 = 10 - 4 = 6$

2nd method: add $4$ to both: $12 - 6 = 16 - 10 = 6$

Both methods give $12 - 6 = 6$

Answer: $6$

1st method: take $2$ out of $8$ first ($8 - 2 = 6$): $72 - 8 = 70 - 6 = 64$

2nd method: add $2$ to both: $72 - 8 = 74 - 10 = 64$

3rd method: $72 - 10 = 62$ and $10 - 8 = 2$, so $72 - 8 = 62 + 2 = 64$

All three methods give $72 - 8 = 64$

Answer: $64$

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

$90 - 10 = 80$

Answer: $80$

1st method (take the tens first): $31 - 18 = 21 - 8 = 20 - 7 = 13$

2nd method: add $2$ to both: $31 - 18 = 33 - 20 = 13$

3rd method: $31 - 20 = 11$ and $20 - 18 = 2$, so $31 - 18 = 11 + 2 = 13$

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

All four methods give $31 - 18 = 13$

Answer: $13$

(i) $240 = 230 + 10$ and $10 - 7 = 3$, so $240 - 7 = 230 + 3 = 233$

(ii) units $4 - 1 = 3$, tens $6 - 4 = 2$, hundreds $4$ stays: $464 - 41 = 423$

Answer: (i) $233$ (ii) $423$

1st method (take the tens first): $382 - 46 = 342 - 6 = 340 - 4 = 336$

2nd method: add $4$ to both: $382 - 46 = 386 - 50 = 336$

3rd method: $382 - 50 = 332$ and $50 - 46 = 4$, so $382 - 46 = 332 + 4 = 336$

4th method (column): $2 < 6$, so borrow $1$ ten: units $12 - 6 = 6$, tens $7 - 4 = 3$, hundreds $3$

All four methods give $382 - 46 = 336$

Answer: $336$

Take away the tens first: $100 - 90 = 10$

$100 - 92 = 10 - 2 = 8$

Answer: $8$

1st method (column): units $1 < 9$, borrow $1$ ten: $11 - 9 = 2$

tens: $0 < 1$, borrow from the hundred: $10 - 1 = 9$, hundreds $0$

2nd method: take $1$ from both: $111 - 19 = 110 - 18$

take $10$ from both: $= 100 - 8 = 92$

3rd method: $111 - 100 = 11$ and $100 - 19 = 81$, so $111 - 19 = 11 + 81 = 92$

All three methods give $111 - 19 = 92$

Answer: $92$

$2$ tens $+$ $7$ tens $=$ $9$ tens

$20 + 70 = 90$

Answer: $90$

Tens: $40 + 90 = 130$

Units: $2 + 1 = 3$

$42 + 91 = 130 + 3 = 133$

Answer: $133$

$17 \div 3$: $3 \times 5 = 15$, $17 - 15 = 2$

Bring down $5$, we have $25$: $3 \times 8 = 24$, $25 - 24 = 1$

Bring down $5$, we have $15$: $3 \times 5 = 15$, $15 - 15 = 0$

Remainder $0$, so $1755 \div 3 = 585$

Answer: $585$

$8 \div 2$: $2 \times 4 = 8$, $8 - 8 = 0$

Bring down $0$, we have $0$: $0 < 2$, so write $0$ in the quotient

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

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

Bring down $6$, we have $6$: $2 \times 3 = 6$, $6 - 6 = 0$

Bring down $9$, we have $9$: $2 \times 4 = 8$, $9 - 8 = 1$

Bring down $2$, we have $12$: $2 \times 6 = 12$, $12 - 12 = 0$

Remainder $0$, so $8044692 \div 2 = 4022346$

Answer: $4022346$

$63 \div 7$: $7 \times 9 = 63$, $63 - 63 = 0$

Bring down $5$, we have $5$: $5 < 7$, so write $0$ in the quotient

Bring down $5$, we have $55$: $7 \times 7 = 49$, $55 - 49 = 6$

Bring down $3$, we have $63$: $7 \times 9 = 63$, $63 - 63 = 0$

Remainder $0$, so $63553 \div 7 = 9079$

Do not miss the $0$ in the quotient.

Answer: $9079$

$21 \div 12$: $12 \times 1 = 12$, $21 - 12 = 9$

Bring down $0$, we have $90$: $12 \times 7 = 84$, $90 - 84 = 6$

Bring down $0$, we have $60$: $12 \times 5 = 60$, $60 - 60 = 0$

Remainder $0$, so $2100 \div 12 = 175$

Answer: $175$

$\displaystyle \frac{12}{4}$ means $12 \div 4$.

$4 \times 3 = 12$, so $\displaystyle \frac{12}{4} = 3$

Answer: $3$