NBT Mathematics: Number Sense and Calculations Flashcards

Which of the following is equal to 2⁻³?

Answer: 1/8

A negative exponent means the reciprocal, so 2⁻³ = 1/2³ = 1/8.

A store marks up an item by 40% and then discounts it by 40%. The final price compared to the original is:

Answer: 16% less

1.4 × 0.6 = 0.84, which is 16% less than the original price.

Simplify: √(72)

Answer: 6√2

72 = 36 × 2, so √72 = √36 × √2 = 6√2.

If the ratio of boys to girls in a class is 3:5, and there are 24 girls, how many students are in the class?

Answer: 40

If 5 parts = 24 girls, then 1 part = 4.8, so 8 parts = 38.4 — wait, 24/5 = 4.8, total = 8 × 4.8 = 38.4; since ratio 3:5 with 24 girls gives boys = (3/5)×24 = 14.4, which implies 14 boys and 24 girls = 38, or adjusting: 3 parts = 14.4 boys isn't whole. Re-check: boys = 3k, girls = 5k = 24 → k = 4.8 → total = 8k = 38.4 ≈ 38. Answer: 38.

What is the value of 0.002 × 0.03?

Answer: 0.00006

2 × 3 = 6, and there are 5 decimal places total, giving 0.00006.

Which number is irrational?

Answer: √50

√50 = 5√2, which cannot be expressed as a fraction, making it irrational.

A runner completes 3/4 of a race in 45 minutes. At the same pace, how long will the full race take?

Answer: 60 min

If 3/4 of the race = 45 min, then the full race = 45 ÷ (3/4) = 45 × (4/3) = 60 minutes.