Answer:
I am useless when together but useful when I am broken apart. What am I?
I eat I live.I breathe I live. I drink I die.
Sing me to a baby about to go to sleep.
I am an odd number. Take away a letter and I become even. What number am I?
Goes over all the hills and hollows, Bites hard, but never swallows.
No matter how little or how much you use me, you change me every month.