rational numbers are fractions (often percents)taxes are a fraction of the income or the purchase amount, so if you spend or earn money, you're involved with fractions.if you share a pizza or a bag of popcorn, you each get a fraction of it.interest rates on loans and mortgages are fractions.interest on a savings account is a fraction.taxes on gasoline are fractions of the amount purchased.if you watch TV, picture has a constant 4/3 width to height ratio.if you listen to music, the tones are in simple fraction relationships (3rds, 5ths, and so on).if you use a flush toilet, the plumber had to know to make the slope of the waste line a basic fraction, 1/4 inch per foot.

if you ride a bike or drive a car, the gear ratios help you accelerate and climb and cruise.