Major Scale: WWHWWWH
Natural Minor Scale: WHWWHWW
Harmonic Minor Scale: Raise the 7th tone of a Natural Minor Scale by a half step
Melodic Minor Scale: Raise the 6th and 7th tones of a Natural Minor Scale by a half step ascending. When descending, use the Natural Minor Scale.
*W = whole step (2 semitones) and H = half step (1 semitone)