Lab assignment [lab2-7]

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When you write a number in base 10, each digit represents how many of a particular power of 10 are in the number. From right to left, the digits represent powers 10⁰, 10¹, 10², ... For example 123 = 1×10² + 2×10¹ + 3×10⁰. To emphasize that the base is 10, we will write 123₁₀.

Computers represent numbers in base 2, not base 10. In base 2, the digits (from right to left) represent powers 2⁰ 2¹, 2², 2³, ... The digits in a number are only allowed to be 0 or 1. For example, 101₂ = 1×2² + 0×2¹ + 1×2⁰ = 5₁₀. The following table shows a few numbers written in base 10 (decimal) and base 2 (binary).

Decimal		Binary
1		1
3		11
4		100
6		110
10		1010
15		1111
16		10000

This problem is similar to the preceding problem, but this time the idea is to count how many of the bits in a binary number are 1. Call the function numOneBits(n). For example, numOneBits(5) = 2 since 5₁₀ is written 101₂ in base 2, and two of the digits are 1. Similarly, numOneBits(15) = 4 since 15₁₀ is written 1111₂ in base 2.

(Note. n `mod` 2 is the rightmost bit of n (written in binary) and n `div` 2 is what you get by removing the rightmost bit. For example, (1101111₂) `mod` 2 = 1 and (1101111₂) `div` 2 = (110111₂).)

Test your definition by pushing the Compute button. After it works, submit it by pushing the Submit button.