PTSot 20.b:59[2] :מאת על מאת בית ארבעת סאין‏ : a hundred times a hundred cubits is an area of four seahs
See the entire entry for məˀā (mā) num. hundred

PTSot 20.b:59[2] :חמשין על חמשין‏ : fifty by fifty (cubits)
See the entire entry for ˁal prep. upon; against; to