Let’s start off easy! Even if you hate math, you should be able to pinpoint that there’s a hidden element as we go from increments of one before jumping from 6 to 9. First things first, though, is how do we justify saying 2 equals 6? Think you’ve got it? All we’re doing is multiplying the top number to the digit below it. But 6 x 9 doesn't equal 42, and therein lies the second part of the equation. Knowing the original count was increments of one, the number below six should be seven, which means the number below 9 would be 10, giving us an answer of 90.