SOLVE FOR
INTEREST
Pick the unknown
ROUNDING
2DP
Money usually 2dp
PRINCIPAL (£)
P
Starting amount
RATE (%)
r
Percent per year
TIME (YEARS)
t
Years (can be decimals)
INTEREST (£)
I
Earned/paid
FINAL AMOUNT (£)
A
A = P + I
WORKING
—
—
—
—
—
INTEREST
READY
—
PAGE 1/2
SOLVE FOR
INTEREST
Pick the unknown
ROUNDING
2DP
Money usually 2dp
PRINCIPAL (£)
P
Starting amount
RATE (%)
r
Percent per year
TIME (YEARS)
t
Years (can be decimals)
INTEREST (£)
I
Earned/paid
FINAL AMOUNT (£)
A
A = P + I
WORKING
—
—
—
—
—
INTEREST
READY
—
PAGE 1/2
FORMULAS
I = P × r × t
A = P + I
r is a decimal (6% → 0.06)
HOW TO USE
1) Pick SOLVE FOR
2) Enter the known values
3) Press SOLVE
4) Read the working lines
WORKED EXAMPLE
P=£500, r=6%, t=3
I = 500×0.06×3
I = £90
A = 500 + 90 = £590
REARRANGE
P = I ÷ (r×t)
r = I ÷ (P×t)
t = I ÷ (P×r)
Use r as a decimal
PAGE 2/2