What table are you using. Here is the instruction from pub 939. You use the multi times the amount your clients expects to receive yearly

Effective July 1, 1986, the IRS adopted new annuity Tables V through VIII, in which your sex isn't considered
when determining the applicable factor. These tables correspond to the old Tables I through IV. In general, Tables
V through VIII must be used if you made contributions to
the retirement plan after June 30, 1986. If you made no
contributions to the plan after June 30, 1986, generally
you must use only Tables I through IV. However, if you received an annuity payment after June 30, 1986, you may
elect to use Tables V through VIII (see Annuity received
after June 30, 1986, later).