I think one math word that starts with B might be 'bisection'. It's not always used in math, but frequently is.
Bi-sect / Bi-sector
Bar graph
Base
Bilateral symmetry
Billion
Billionth
Box
Brackets
B
I
D
M
A
S
· eight
· eighteen
· eighty
· eleven
· equal
· equation
· equilateral triangle
· estimate
· exponent
Equation, perhaps?
Euler
Bivariate. As in bivariate data (a statistics NCEA Level 1 internal topic).
agreeagreementegretogle
Entropy is a synonym for chaos. It begins with the letter e.
How about Greece, as in the country.
automobile
endorphins
# duels # duets
Exponents, equals
· eggplant
Some math words beginning with the letter E are:EqualsEquationEquilateralEvaluateExpandExpression
Aisle
Elbow, Ear, Eye...
lake Eire or however you spell it.
exponent
minte pie nshajshskuad
equation
Beetle is a 6 letter word that has 'e' as the third letter.
· Easter Lamb Cake · Éclair · Eggnog Ice Cream