Your question has been over 1 year old. Probably you bought that property already! Anyway, for your information:
No fix number for Multiplier. To find the Multiplier:
1- Find the recent sales in the area: ideal is within 1/2 mile (up to 1mile) and 6 months back in time (up to 1 year). Keep finding until you can find atleast 5 sales. Note: these sales should have same number of units or just +/- 1. That means: do not use 3 units sale if your subject is 5 units (unless you find no others)
2- Divide the sale price of each sale by its estimated GROSS INCOME to have that sale's multiplier. You then have a range of the multipliers in the area.
3- Do the reconcile: more weight on the properties with same number of units, bedrooms.
James Bui - Realtor