What is the postal code for 7 420 hunters green edmonton ab?

That should be
T5C 2R5

You can look up Postal Codes on the CanadaPost website : Find A Postal Code

https://www.canadapost.ca/cpo/mc/personal/postalcode/fpc.jsf

51107 RANGE ROAD 221
SHERWOOD PARK AB T8E 1G8

https://www.canadapost.ca/cpo/mc/personal/postalcode/fpc.jsf
enter the address.

I get T5T 1B1
I am assuming that it is 23 WESTRIDGE RD NW - the compass point is significant in many cities, and there may be two completely seprarate addresses on the same road NW vs SE for example

17418 98A Avenue EDMONTON T5T 6G2 : Zone 20

It's T5A 3E6
You might find this link interesting-
3819 132 Avenue Northwest Edmonton AB T5A 3E6 Edmonton

T5L 3R8

You might try here. Do you have a 'sub-division'?

http://www.geonames.org/postalcode-search.html?q=EDMONTON&country=CA&adminCode1=AB

Go to: http://www.canadapost.ca/cpo/mc/personal/postalcode/fpc.jsf#
and enter the address.

178 OEMING RD NW
EDMONTON AB T6R 2G2

London postal districts are correctly prefixed with the post town 'LONDON'.

London postal district | London East Central
EC1 Head District | EC2 Bishopsgate | EC3 Fenchurch Street | EC4 Fleet Street

London postal district | London West Central
WC1 Head District | WC2 Strand

London postal district | London North
N1 Head District | N2 East Finchley | N3 Finchley | N4 Finsbury Park | N5 Highbury | N6 Highgate

N7 Holloway | N8 Hornsey | N9 Lower Edmonton | N10 Muswell Hill | N11 New Southgate | N12 North Finchley

N13 Palmers Green | N14 Southgate | N15 South Tottenham | N16 Stoke Newington | N17 Tottenham

N18 Upper Edmonton | N19 Upper Holloway | N20 Whetstone | N21 Winchmore Hill | N22 Wood Green

London postal district | London North West
NW1 Head District | NW2 Cricklewood | NW3 Hampstead | NW4 Hendon | NW5 Kentish Town | NW6 Kilburn

NW7 Mill Hill | NW8 St John's Wood | NW9 The Hyde | NW10 Willesden | NW11 Golders Green

London postal district | London East

E1 Head District | E2 Bethnal Green | E3 Bow | E4 Chingford | E5 Clapton | E6 East Ham | E7 Forest Gate | E8 Hackney | E9 Homerton | E10 Leyton | E11 Leytonstone | E12 Manor Park | E13 Plaistow | E14 Poplar | E15 Stratford | E16 Victoria Dock | E17 Walthamstow | E18 Woodford
London postal district | London West
W1 Head District | W2 Paddington | W3 Acton | W4 Chiswick | W5 Ealing

W6 Hammersmith | W7 Hanwell | W8 Kensington | W9 Maida Vale | W10 North Kensington

W11 Notting Hill | W12 Shepherds Bush | W13 West Ealing | W14 West Kensington

London postal district | London South East
SE1 Head District | SE2 Abbey Wood | SE3 Blackheath | SE4 Brockley | SE5 Camberwell | SE6 Catford | SE7 Charlton

SE8 Deptford | SE9 Eltham | SE10 Greenwich | SE11 Kennington | SE12 Lee | SE13 Lewisham | SE14 New Cross

SE15 Peckham | SE16 Rotherhithe | SE17 Walworth | SE18 Woolwich | SE19 Upper Norwood | SE20 Anerley

SE21 Dulwich | SE22 East Dulwich | SE23 Forest Hill | SE24 Herne Hill | SE25 South Norwood | SE26 Sydenham

SE27 West Norwood | SE28 Thamesmead

London postal district | London South West
SW1 Head District | SW2 Brixton | SW3 Chelsea | SW4 Clapham | SW5 Earls Court

SW6 Fulham | SW7 South Kensington | SW8 South Lambeth | SW9 Stockwell | SW10 West Brompton

SW11 Battersea | SW12 Balham | SW13 Barnes | SW14 Mortlake | SW15 Putney

SW16 Streatham | SW17 Tooting | SW18 Wandsworth | SW19 Wimbledon | SW20 West Wimbledon