Indeed, it's when you have -
...two, three, seven, and ten in English, Latin, Greek and Sanskrit - ie
English
Latin
Greek
Sanskrit
as in -
two
duo
dúo
dva
three
tres
treîs
tráyas
seven
septem
heptá
saptá
ten
decem
déka
dasa
The threes are alike in all the languages ie -
English
Latin
Greek
Sanskrit
three
tres
treîs
tráyas
but linguists are interested in discovering regular patterns, not isolated resemblances. So here, "t" in English often appears as "d" in the other languages,
English
Latin
Greek
Sanskrit
two
duo
dúo
dva
ten
decem
déka
dasa
and "h" in Greek appears as "s" in English, Latin, and Sanskrit.
English
Latin
Greek
Sanskrit
seven
septem
heptá
saptá..."
Then you have the mother of all words - 'ma' perhaps from the suckling sound of babe at breast?