Exercise 2f Natural Numbers

James wants to cover a floor measuring 90cm by 120cm with square tiles of the same size. Given that he uses only whole tiles, find:

a. the largest possible length of the side of each tile,

b. The number of tiles that are needed to cover the floor.

• a. 20cm

  b. 15

• a. 30cm

  b. 12

• a. 32cm

  b. 15

• a. 38cm

  b. 10

Two lighthouses flash their lights every 20 seconds and 30 seconds respectively. Given that they flash together at 3pm, when will they next flash together?

• 3.01pm

• 3.05pm

• 3.11pm

• 3.15pm

Three cyclists A, B and C cycled at a steady ride round a track in 12 min, 18 min and 24 min respectively. If they started together at 10 a.m. at the same point on the track in the same direction, at what time they meet again at the starting point?

• 3.45pm

• 10.15am

• 11.12am

• 12.12pm

A teacher distributes 255 pencils, 425 sheets of graph paper and 595 sheets of writing paper equally to a group of students.

Calculate the largest possible number of students in the group.

• 85

• 90

• 75

• 70

A packet of sweets can be distributed evenly to 15 persons, 20 persons or 25 persons, find the least number of sweets in the packet.

• 320

• 200

• 250

• 300

What is the least length of string which can be cut into equal portions each of 4 em, or into equal portions each of 8 cm, or into equal portions each of 6 cm, without any remainder string?

• 32cm

• 24cm

• 25cm

• 30cm

Find the greatest number that divides 84, 108 and 192 without any remainder.

• 12

• 24

• 25

• 28

Find the greatest natural number such that the remainder is 6

when it divides 90, 146 and 230.

• 18

• 25

• 28

• 32

Find the smallest number such that the remainder is always 2

when it is divided by 10. 15 and 18.

• 15

• 30

• 80

• 92

Find the smallest number such that the remainder is 3

when it is divided by 16, 20 or 24.

• 200

• 225

• 250

• 243