((5 * N + 6) DIV 7) * BS_PA_MFRMS / 4

hi,
Description from 3GPP TS45008:

Whilst in idle mode an MS shall continue to monitor all BCCH carriers as indicated by the BCCH allocation (BA See table 1). A running average of received signal level (RLA_C) in the preceding 5 to:
Max {5 , ((5 * N + 6) DIV 7) * BS_PA_MFRMS / 4}
seconds shall be maintained for each carrier in the BCCH allocation. N is the number of non serving cell BCCH carriers in BA and the parameter BS_PA_MFRMS is defined in 3GPP TS 45.002.

anyone knows what is 7 and 4 in The formula: Max {5 , ((5 * N + 6) DIV 7) * BS_PA_MFRMS / 4}?