1. Problem: Find the circumference of a truck tyre with diameter 70 cm. The formula for circumference is $$C = \pi d$$ where $d$ is diameter. Calculate: $$C = \pi \times 70 = 70\pi \approx 219.91\text{ cm}$$. 2. Problem: Find the digit to add to 936427 to make it divisible by 11. Rule: A number is divisible by 11 if the difference between the sum of digits in odd and even positions is a multiple of 11. Digits: 9(1),3(2),6(3),4(4),2(5),7(6), plus digit $x(7)$. Sum odd positions: $9+6+2+x = 17 + x$. Sum even positions: $3+4+7 = 14$. Difference: $(17 + x) - 14 = 3 + x$. We want $3 + x \equiv 0 \pmod{11}$, so $x = 8$. 3. Problem: Sum of prime numbers between 70 and 80. Primes are 71, 73, 79. Sum: $71 + 73 + 79 = 223$. 4. Problem: Round 3564239801 to nearest tens of millions. Tens of millions place is the 8th digit from right (counting units as 1st). Digit at tens of millions place: 5 (in 3564239801). Next digit (millions place) is 6, which is $\geq 5$, so round up. Rounded number: $3600000000$. 5. Problem: Construct line AB = 6cm, drop perpendicular at A of length 4cm to point C, find length BC. Right triangle ABC with legs $AB=6$ cm and $AC=4$ cm. Use Pythagoras theorem: $$BC = \sqrt{AB^2 + AC^2} = \sqrt{6^2 + 4^2} = \sqrt{36 + 16} = \sqrt{52} = 2\sqrt{13} \approx 7.21\text{ cm}$$. 6. Problem: Find hypotenuse $c$ of right triangle with legs 9 cm and 12 cm. Use Pythagoras theorem: $$c = \sqrt{9^2 + 12^2} = \sqrt{81 + 144} = \sqrt{225} = 15\text{ cm}$$. 7. Problem: Convert $\frac{6}{25}$ to decimal. Divide 6 by 25: $6 \div 25 = 0.24$. 8. Problem: Convert decimal 0.136 to fraction. $0.136 = \frac{136}{1000} = \frac{17}{125}$ after simplification. 9. Problem: Calculate $(1.36)^2$. Calculate: $1.36 \times 1.36 = 1.8496$. 10. Problem: Place value of digit 4 in 0.0148. Digit 4 is in the thousandths place. 11. Problem: Calculate area of circle with radius 10.5 cm. Formula: $$A = \pi r^2$$. Calculate: $$A = \pi \times (10.5)^2 = \pi \times 110.25 \approx 346.36\text{ cm}^2$$. 12. Problem: Calculate area of trapezium with parallel sides 9 cm and 14 cm, height 8 cm. Formula: $$A = \frac{(a+b)}{2} \times h$$. Calculate: $$A = \frac{(9+14)}{2} \times 8 = \frac{23}{2} \times 8 = 11.5 \times 8 = 92\text{ cm}^2$$.