1 ) I always picked a few numbers between half of the whole and the whole number, just because the percentage of the number is more than half. and then after i went through the series of numbers, by dividing the number i picked to the percentage, and multiply by 100. so for example,
24.79/67 = .37 × 100 = 37. Its definitely not the most accurate, but it has never messed me up before.
2 ) or you could do 67/100 × 37. I mean the version is the most accurate and fastest way. But I have always liked my way.
Hope this Helps. Definitely Listen to number 2 :)