The traditional view is that 'less' applies to matters of degree, value, or amount and modifies collective nouns, mass nouns, or nouns denoting an abstract whole while 'fewer' applies to matters of number and modifies plural nouns. 'Less' has been used to modify plural nouns since the days of King Alfred and the usage, though roundly decried, appears to be increasing. 'Less' is more likely than 'fewer' to modify plural nouns when distances, sums of money, and a few fixed phrases are involved. #f

Finding a Least Common Multiple (With Variables)

SAT/ACT Math Trick: Find the Least Common Multiple (LCM) Quickly