Rab Cap multiplying wrong with Archmage

Rab Cap is 35% Archmage is 5% They are not additive 35+5 = 40 They are multiplicative 35% * 5% = 41.75% However, they are giving 44% This nearly doubles the effectiveness of Archmage

Rab cap 35% archmage 5% dragon buff 5% if additive would be 45% Its not additive, its multiplicative should give 48.8% However all 3 are giving 51.2%