Question paper, Set 9

(i) Start at $4$ and count on $2$: $4 + 2 = 6$

(ii) Count back $4$ from $8$: $8 - 4 = 4$

Answer: (i) $6$ (ii) $4$

(i) $\square = 8 - 6 = 2$ (check: $6 + 2 = 8$)

(ii) $\square = 10 - 3 = 7$ (check: $3 + 7 = 10$)

Answer: (i) $2$ (ii) $7$

$\square = 8 - 1 = 7$

Check: $1 + 7 = 8$

Answer: $7$

(i) $50 = 40 + 10$ and $10 - 5 = 5$, so $50 - 5 = 40 + 5 = 45$

(ii) $40 = 30 + 10$ and $10 - 2 = 8$, so $40 - 2 = 30 + 8 = 38$

Answer: (i) $45$ (ii) $38$

Take $8$ from the units digit: $9 - 8 = 1$; the tens digit $8$ stays.

$89 - 8 = 81$

Answer: $81$

1st method: take $5$ out of $7$ first ($7 - 5 = 2$): $15 - 7 = 10 - 2 = 8$

2nd method: add $3$ to both: $15 - 7 = 18 - 10 = 8$

Both methods give $15 - 7 = 8$

Answer: $8$

1st method: take $2$ out of $8$ first ($8 - 2 = 6$): $32 - 8 = 30 - 6 = 24$

2nd method: add $2$ to both: $32 - 8 = 34 - 10 = 24$

3rd method: $32 - 10 = 22$ and $10 - 8 = 2$, so $32 - 8 = 22 + 2 = 24$

All three methods give $32 - 8 = 24$

Answer: $24$

$7$ tens $-$ $4$ tens $=$ $3$ tens

$70 - 40 = 30$

Answer: $30$

1st method (take the tens first): $92 - 69 = 32 - 9 = 30 - 7 = 23$

2nd method: add $1$ to both: $92 - 69 = 93 - 70 = 23$

3rd method: $92 - 70 = 22$ and $70 - 69 = 1$, so $92 - 69 = 22 + 1 = 23$

4th method (column): $2 < 9$, so borrow $1$ ten: units $12 - 9 = 3$, tens $8 - 6 = 2$

All four methods give $92 - 69 = 23$

Answer: $23$

(i) $140 = 130 + 10$ and $10 - 9 = 1$, so $140 - 9 = 130 + 1 = 131$

(ii) units $6 - 6 = 0$, tens $5 - 3 = 2$, hundreds $2$ stays: $256 - 36 = 220$

Answer: (i) $131$ (ii) $220$

1st method (take the tens first): $440 - 16 = 430 - 6 = 424$

2nd method: add $4$ to both: $440 - 16 = 444 - 20 = 424$

3rd method: $440 - 20 = 420$ and $20 - 16 = 4$, so $440 - 16 = 420 + 4 = 424$

4th method (column): $0 < 6$, so borrow $1$ ten: units $10 - 6 = 4$, tens $3 - 1 = 2$, hundreds $4$

All four methods give $440 - 16 = 424$

Answer: $424$

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

$100 - 16 = 90 - 6 = 84$

Answer: $84$

1st method (column): units $3 < 4$, borrow $1$ ten: $13 - 4 = 9$

tens: $0 < 5$, borrow from the hundred: $10 - 5 = 5$, hundreds $0$

2nd method: take $3$ from both: $113 - 54 = 110 - 51$

take $10$ from both: $= 100 - 41 = 59$

3rd method: $113 - 100 = 13$ and $100 - 54 = 46$, so $113 - 54 = 13 + 46 = 59$

All three methods give $113 - 54 = 59$

Answer: $59$

$4$ tens $+$ $3$ tens $=$ $7$ tens

$40 + 30 = 70$

Answer: $70$

Tens: $50 + 90 = 140$

Units: $2 + 6 = 8$

$52 + 96 = 140 + 8 = 148$

Answer: $148$

$27 \div 7$: $7 \times 3 = 21$, $27 - 21 = 6$

Bring down $5$, we have $65$: $7 \times 9 = 63$, $65 - 63 = 2$

Bring down $8$, we have $28$: $7 \times 4 = 28$, $28 - 28 = 0$

Remainder $0$, so $2758 \div 7 = 394$

Answer: $394$

$7 \div 2$: $2 \times 3 = 6$, $7 - 6 = 1$

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

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

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

Bring down $1$, we have $11$: $2 \times 5 = 10$, $11 - 10 = 1$

Bring down $1$, we have $11$: $2 \times 5 = 10$, $11 - 10 = 1$

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

Remainder $0$, so $7699110 \div 2 = 3849555$

Answer: $3849555$

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

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

Bring down $1$, we have $1$: $1 < 2$, so write $0$ in the quotient

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

Remainder $0$, so $4016 \div 2 = 2008$

Do not miss the $0$ in the quotient.

Answer: $2008$

$47 \div 12$: $12 \times 3 = 36$, $47 - 36 = 11$

Bring down $5$, we have $115$: $12 \times 9 = 108$, $115 - 108 = 7$

Bring down $2$, we have $72$: $12 \times 6 = 72$, $72 - 72 = 0$

Remainder $0$, so $4752 \div 12 = 396$

Answer: $396$

$\displaystyle \frac{18}{3}$ means $18 \div 3$.

$3 \times 6 = 18$, so $\displaystyle \frac{18}{3} = 6$

Answer: $6$