Question

A greeting card has an area 90 cm². Between what two whole numbers is the length of its side?

Answer 1

1	90
5	45
3	9
3	3
	1

Area of the greeting card = 90 cm²

(side)² = 90 cm²

(side)² = 2 × 5 × 3 × 3 = 2 × 5 × 3² 

${\displaystyle \sqrt{{\left(\text{side}\right)}^2}=\sqrt{2\times 5\times 3^2}}$

side = ${\displaystyle 3\sqrt{2\times 5}}$

side = ${\displaystyle 3\sqrt{10}}$ cm

side = 3 × 3.2 cm

side = 9.6 cm

∴ Side lies between the whole numbers 9 and 10.