Dates
In English, we can say dates either with the day before the month, or the month before the day:
The first of January / January the first.

Remember to use ordinal numbers for dates in English.
(The first, the second, the third, the fourth, the fifth, the twenty-second, the thirty-first etc.)

Years
For years up until 2000, separate the four numbers into two pairs of two:
1965 = nineteen sixty-five
1871 = eighteen seventy-one
1999 = nineteen ninety-nine

For this decade, you need to say "two thousand and —-" when speaking British English:
2001 = two thousand and one
2009 = two thousand and nine

Large numbers
Divide the number into units of hundreds and thousands:
400,000 = four hundred thousand (no s plural)

If the number includes a smaller number, use "and" in British English:
450,000 = four hundred and fifty thousand
400,360 = four hundred thousand and three hundred and sixty

Fractions, ratios and percentages
½ = one half
1/3 = one third
¼ = one quarter
1/5 = one fifth
1/ 6 = one sixth etc
3/5 = three fifths

1.5% = one point five percent
0.3% = nought / zero point three percent

2:1 = two to one

Saying 0
Depending on the context, we can pronounce zero in different ways:
2-0 (football) = Two nil
30 – 0 (tennis) = Thirty love
604 7721 (phone number) = six oh four…
0.4 (a number) = nought point four / zero point four
0C (temperature) = zero degrees

Talking about calculations in English
+ (plus)
2 + 1 = 3 (two plus one equals three)
- (minus / take away)
5 – 3 = 2 (five minus three equals two / five take away three equals two)
x (multiplied by / times)
2 x 3 = 6 (two multiplied by three equals six / two times three equals six)
/ (divided by)
6 / 3 = 2 (six divided by three equals two)