Decimal {2} ldec_start
Decimal {2} ldec_percent
Decimal {2} ldec_years
Decimal {2} ldec_annual
Decimal {2} ldec_balance

ldec_start = Dec(sle_start.text)
ldec_percent = Dec(sle_interest.text)
/ 100
ldec_years = Dec(sle_year.text)
ldec_annual = Dec(sle_annual.text)

ldec_balance = ldec_start * ((1 +
ldec_percent) ^ ldec_years )

ldec_balance += ldec_annual * ( ((1 +
ldec_percent) ^ (ldec_years + 1) -
(1 + ldec_percent))/ldec_percent)

sle_balance.text = String(ldec_balance)

Listing 2: Rule of 72 implementation

Decimal {2} ldec_exact
Decimal {2} ldec_rule72
Decimal {2} ldec_calc

ldec_calc = Dec(sle_rate.text)

IF rb_fwd.checked = TRUE THEN //Forward
ldec_exact = log(2)/log(1 + ldec_calc/100)
ldec_rule72 = 72/ldec_calc
ELSE //Backward
ldec_exact = (Exp(log(2)/ldec_calc) -
1) * 100
ldec_rule72 = 72/ldec_calc
END IF

sle_exact.text = String(ldec_exact)
sle_rule72.text = String(ldec_rule72)