The number on the pack is weight rather than quantity, which is why two 100 gram boxes can hold very different counts. Size the band to the bundle relaxed rather than stretched, since a band working near its limit hardens and snaps within weeks. Heat and light age them regardless, so store away from a window. See Bounce rubber bands, 25g rubber bands and office supplies.

Bounce 100g rubber bands and dispenser on a bright office desk with stationery and filing supplies.
Rubber Bands For Office And Everyday Organisation

Shop rubber bands for office, mailroom, school and home organisation at Mega Office Supplies.