Work out simple interest (I = P × r × t) and the total amount. Live results.
Interest = Principal × rate × time, where the rate is a decimal (5% = 0.05) and time is in years. The total you'll have is principal + interest.
Simple interest is charged only on the original principal. Compound interest is charged on the principal plus previously accrued interest, so it grows faster — use the compound interest tool for that.
Yes — enter the time as a fraction of a year. Six months is 0.5, three months is 0.25.