Math Calculation Shortcut?

[SyrianHero]

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Is there an easy way to subtract 2 numbers with large exponents on the MCAT? For example,
(1.5*10^15) - (5*10^14)?

 

[sanrose]

I always make the same exponent, then I subtract the bases. For example:

15*10^14 - (5 * 10^14)
= 10*10^14
= 1* 10^15