What is the big formula for January, February and March?

January is big, February is flat, March is big, April is small, May is big, June is small, July is big, August is big, September is small, October is big, November is small and December is big.

Make a fist with one hand, except the thumb. Look at the knuckles where the back of your hand meets your fingers. From the index finger to the little finger, the protrusions are 1, 3, 5, 7, and the depressions are 2, 4, 6. Then from the index finger to the ring finger, the protrusion is 8, 10 and the depression is 9.

The memory method of big and small moons is jingle.

1, 3, 5, 7, 8, 10, La, (Da Yue) 3 1 day is never bad.

4, 6, 9, 1 1, (abortion) 30 days without change of heart. ?

February is flexible, with 28 in a normal year and 29 in a leap year.