Because it cannot be anything else.
38
Three plus six equals nine.
Six.
Three minus three times six plus two is equal to -13.
Six
81 + 63 = 144
Three and three fourths plus three is six and three fourths.
(Three of anything) plus (another three of it) = (six of the same thing)
Four plus three multiplied by six times three to the power of four is equal to 1,462.
three plus one tenth plus six thousandths equals three and one hundred and six thousandths
Eight and five over six plus six and three over eight = 365/24 or 155/24
3 + 3 = 6, or three plus three equals six.