A number leaves a remainder of 20 when divided by 28. What is the remainder when the same number is divided by 7?
Answer: C
Let the number be N. We are given N = 28k + 20 for some integer k. We want to find the remainder when N is divided by 7. We can write N as \( (4 \times 7)k + (3 \times 7 - 1) \). This is not helpful. Let's use a simpler method. Since 28 is a multiple of 7, we can find the required remainder by simply dividing the first remainder (20) by the new divisor (7). Remainder = \(20 \div 7\). \(20 = 2 \times 7 + 6\). The remainder is 6.